Continuous blow-off for steam boilers



Nov. 2, 1937 O H. F. sHAw 2,097,648

CONTINUOUS BLOW-OFF FOR STEAM BOILERS Filed July 50, 1936 V 1&4.

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Patented Nov. 2, 1937 UNITED STATES PATENT OFFICE CONTINUOUS BLOW-OFF FOR STEAM BOILE 2 Claims.

This invention relates to steam boilers and particularly to continuous blow-oil means for steam boilers.

Nearly every steam boiler in operation has trouble with insoluble and soluble substances present in its feed water supply as these substances tend to deposit or form scale on the boiler walls. Frequently the problem is aggravated, due to the fact that the boiler has several sources, or a variable source, of feed-water. Most boilers are provided with means for treating the feed-water and for draining or filtering off the insoluble matter present in it. However, these means are ordinarily not adapted to be conveniently changed in order to compensate for variations in the amounts of insoluble and soluble material present in the feedwater. Then too, the rate of evaporation varies with the load on the boiler so that a considerable variation occurs in the volume of water passing through the boiler in a given time.

One of the methods used at present to prevent depositing soluble and insoluble materials in the boiler is to continuously withdraw water from the bottom of the boiler. By doing this, the concentration of the soluble matter in the water is kept down and the insoluble matter both in suspension and that settling to the bottom of the boiler is withdrawn. The withdrawal of water is effected by blow-01f means which must be adapted to take care of the maximum evaporation load of the boiler and, therefore, a considerable loss of boiler water and heat follows when the load is decreased. This loss occurs because the blow-01f means is adapted to withdraw the amount of water necessary for proper functioning of the boiler at full load and a much smaller amount of water can be withdrawn at lighter loads and still prevent any deposit of solids on the boiler.

An object of this invention is to provide inexpensive blow-ofl means which is easily and rapidly changeable with the condition of the feedwater and the load on the boiler, and which is adapted to prevent insoluble as well as'soluble matter from depositing on the boiler.

The above and other objects of the invention will be apparent from the following description and drawing in which: v

Figure 1 is a diagrammatic view of two boiler systems having the apparatus'oi this invention connected therein;

Figure 2 is an elevation oi one embodiment of my invention; and

Figure 3 is a plan of the orifice plate.

Referring to Figure 1 of the drawing, my invention is shown connected to mud drums 4 of boilers 2 and 3. The pipes 5 are connected to the bottom of the boilers Z and 3 so that they removethe water which contains most of the insoluble matter and a high concentration of the soluble matter present in the boiler water. The drum 4 is always filled with water as long as any water is present in the boilers 2 and 3. There are no obstructions between the boilers and the drums 4, so that the water in the drum 4 is at the boiler pressure.

Pipes 6 connect to or near the bottom of the drum 4 at several difierent places. However, in some cases it may be expedient to connect the pipes 6 directly to the boilers 2 and 3. The pipes 6 extend downwardly and unite to form a pipe 1 which connects a blow-off chamber 8 with the drums 4. Valves 9 in the pipes I prevent water from flowing into the chamber 8 when the chamber 8 is to be cleaned, or at any other time when water flow into the chamber 8 is not desired.

It will be appreciated that the water pressure in the chamber 8 and throughout the system is at substantially the boiler pressure. The apparatus is designed to withstand such pressure and is provided with suitable gaskets at any flanged connections in the enclosure means.

The specific connection of the pipes 6 depends upon the amount of insoluble and soluble material ordinarily present in the feed-water. For example, river steamers use river water in their boilers and, as a rule, must remove a large amount of insoluble material present in the water so that the boilers are provided with mud drums as illustrated in Figure 1. The connection illustrated in Figure 1 is particularly adapted to remove insoluble material present in the boiler but it also serves to keep the concentration oi the soluble matter down so that it does not precipitate.

The chamber 8 has flanges I8 and II on its ends which are connected to plates l2 and I3 respectively by bolts so that the chamber 8 is water-tight but still readily accessible for repair or cleaning purposes. The plate l2 has two tapped apertures through it, in one of which the end of the pipe I is received. The bore of the pipe 1 is tapped adjacent its end and receives a pipe 14 which extends into the chamber 8 more than half the length of the chamber 8.

As shown in Figure 2, a pipe I6 is threaded into the other tapped aperture through the plate l2 and is connected to a pipe 28 of a larger diameter than the pipe l6 by means of ells H and 55 18. The pipe engages with a circular plate 22 which is connected to a plate 24 by bolts 28.

A plate 28, having a circular portion substantially larger than the pipe 20 and provided with an orifice 29 through its center, is positioned between the plates 22 and 24. Preferably one of the bolts 26 extends through an aperture 38 formed in a fiat handle 3| integral with the plate 28 and serves to hold the plate 28 between the plates 22 and 24. This makes it easier to position the orifice 29 approximately in the center of the pipe 28; of course, the plate 28 can be held between the plates 22 and 24 without inserting a bolt in the aperture 30. A pipe 32, connected to the plate 24, is aligned with the pipe 28 and orifice 29 so that it receives the water discharged through the orifice 29. The pipe 32 is provided with a valve 34 and connects to a drain pipe 38 which can serve several boilers. The water in the pipe 20 is at approximately the boiler pressure but once through the orifice 29, the pressure on the water drops and it is discharged by gravity.

In operation, as soon as a valve 9 is opened, water flows from the bottom of the drums 4, through the pipes 6 and 1 to the chamber 8. This water contains nearly all the insoluble matter present in the water in the drums 4, and also a high concentration of the soluble matter present in the boiler water. The pipe l4 introduces the blow-ofi water near the bottom of the chamber 8 and, as the discharge pipe I6 is in the top of the chamber 8, some of the insoluble matter settles out in the chamber 8. When the water flows out of the chamber 8 through the pipe I6 and reaches the pipe 28, it meets the plate 28. Then,as the boiler pressure is practically constant, the amount of water discharged into the pipe 36 through the orifice 29 can be directly controlled by varying the size of the orifice in the system.

In order to change the size of the orifice 29, a plate having a different diameter orifice is substituted for the plate 28. The size of the orifice is preferably varied by changing the plates 28 instead of having a valve or other variable size orifice, as the plates 28 are inexpensive, not noticeably injured by long use and rapidly changed. To change the plates 28, the valve 9 should be closed to remove the boiler pressure 'from the system so that the chamber 8 can be drained. A pipe 38 is received in the flange 13 so that the chamber 8 can be drained when desired. The pipe 38 is provided with a valve 48 which, when opened, permits water to flow out of the chamber 8 to the pipe 36 which empties into a sewer or other convenient discharge means. When the valves 34 and 40 are closed no steam or hot water can be blown back from the drain pipe 36 and interfere with the workman changing the plates. After that, if the bolts 26 are loosened slightly and the one through the aperture taken out, the plate 28 can be removed and a similar plate having the desired size orifice can be substituted. The bolt having been replaced and tightened, the valves 9 and 34 are opened and the blow-off is back in use. This entire operation can be done rapidly and by one man using no other equipment than an ordinary nut wrench so that it is a practical operation even for slight variations in the boilers condition.

The effect produced by this continuous stream of water discharging from the boiler is to prevent any insoluble matter'from depositing in the boiler as it is bodily removed from the boiler. Then too, the blow-ofi water is, in effect, taken from the boiler itself in each case so that added protection results in that the concentration of any soluble material present in the feed-water is kept low enough to prevent crystallization of such material to form boiler scale.

It will be appreciated that the scope of the invention is not limited to the specific form illustrated and described, but is actually defined in the appended claims.

I claim:

1. Blow-ofi means for steam boilers comprising a chamber, means adapted to feed a continuous stream of Water to said chamber from a point near the bottom of a mud drum which is connected to a boiler, means adapted to introduce said water stream into said chamber near its bottom, overflow means in the top of said chamber whereby water flows from said chamber when it is full, discharge means for said overflow water, readily removable means connecting said overflow means and said discharge means and a plate having a circular portion provided with an orifice therethrough adapted to fit between said removable means and align said orifice with said overflow and said discharge means, said plate being provided with a handle portion for facilitating the proper positioning of said orifice.

2. Blow-off means for steam boilers comprising a chamber, means for feeding a continuous stream of water from a point near the bottom of the boiler to said chamber, overflow means for permitting water to flow from said chamber when it is substantially full, discharge means for he water overflowing said chamber, said discharge means and said overflow means being secured together by a flanged connection, a plate adapted to be received between the flanges of said flanged connection and provided with a handle portion that is constructed and arranged to extend be- I yond said flanged connection for aiding in positioning said plate, said plate having an orifice therein, and means for removably locking said plate between the flanges of said flanged connection.

HARRY FREDERICK SHAW. 

